Dewaxing machine



Aug. 13, 195 P. D. LABOMBARDE DEWAXING MKCHINE 4 Sheet s-Sheet 1 Filed Feb. 9, 1955 a a a 2% 1N VEN TOR. PHILIP D. .LABOJVIBARDE' 4 4 1 7:) ATTORNEYS Aug. 13, 1957 P. D. LABOMBARDE 2,302,926

DEWAXING MACHINE Filed Feb. 9, 1955 4 Sheets-Sheet 2 INVENTOR.

PHILIP D.'LAB01\1BA RDE BY 1 p e 4 a +7 ATTORNEYS Aug. 13, 1957 P. D. LABOMBARDE DEWAXING MACHINE 4 Sheets-Sheet 3 Filed Feb 9, 1 955 P ik cm cm 5 182 1&5 53

8. INVENTOR. PEILD D LABOJVIBARDE ATTORNEYS Aug. 13, 1957 P. D. LABOMBARDE 2,302,926

DEWAXING MACHINE Filed Feb. 9, 1955 4 Sheets-Sheet 4 LINVENTOR.

PHILIP D. LABOJUBARDE ATTORNEYS United States PatentO DEWAXING MACHINE Philip D. Labombarde, Nashua, N. H.

Application February 9, 1955, Serial No. 487,053 12 Claims. (Cl. 219-19 This invention relates to machines for automatically removing coating from coated flat box blanks, in preselected spots only, to facilitate the gluing of the same when folded into a box. Such machines are sometimes termed dewaxers, since blanks intended to form frozen food cartons, or the like, are usually coated on both faces with wax.

In U. S. Patent. No. 2,602,416 to Perilli issued July 8, 1952 a machine for the above purpose is described wherein a reciprocable carriage moves back and forth along the paper line and a blank is clamped between electrically heated elements on the forward movement of the carriage. At the end of the forward travel of the carriage the clamps move apart and the blank is extracted in a forward direction therefrom by an upper and lower conveyor belt.

In this invention no such reciprocating carriage is used, the electrically heated elements move only on a fixed axis relative to the machine and no extracting means is used. Instead an endless conveyor pushes each blank between the heated elements, releases the blank for dewaxing and then pushes the blank away from the heating elements in a resumption of its forward movement.

An object of the invention is to provide a simplified machine for treating blanks at a treatment station wherein a continuously moving endless conveyor releases each successive blank at the station for treatment and sub sequently re-engages the blank to move it away from the station after treatment.

Another object of the invention is to provide novel mounting means for the electrically heated members of the apparatus wherein said members are spring pressed toward each other at a predetermined pressure and forced apart by cam mechanism.

Still another object of the device is to provide blank retarding means which cooperates with the endless conveyor of the invention to firmly hold each blank in registration on the conveyor.

A still further object of the invention is to provide blank clamping means cooperable with the endless conveyor and heating members of the invention and with the blank retarding means for holding the blank down and stationary during the movement of the heating members.

Another object of the invention is to provide mechanism whereby the heated elements each move away from the blank after treatment and the blank is engaged at its trailing edge by register lugs to move it forwardly from the treatment position, thereby avoiding any possible slippage and overcoming any tendency of the blanks to stick to the heating elements.

In the drawings Fig. 1 is a plan view of a machine constructed in accordance with the invention,

Fig. 2 is a fragmentary plan view of one type of box blank having a coating such as wax on both faces thereof,

Fig. 3 is a view similar to Fig. 2 showing heating elements being applied to both faces of certain flaps or tabs of the blank, 2

2,802,926 Patented Aug. 13, 1957 Fig. 4 is a view similar to Fig. 3 but with the corner tabs folded back to show the decoated areas thereof,

Fig. 5 is a side elevation of the machine shown in Fig. 1 with parts broken away,

Fig. 6 is a side view in section on line 6-6 of Fig. 1 showing a blank released by the conveyor at the heating station,

Fig. 7 is a view similar to Fig. 6 showing the blank after decoating being engaged by the alternate fixed register lugs of the conveyor,

Fig. 8 is an end view in section on line 88 of Fig. 5,

Fig. 9 is an enlarged fragmentary side elevation showing the means for moving the heating members toward and away from each other,

Fig. 10 is a view similar to Fig. 9 of the heating members in closed, heating position and Fig. 11 is a fragmentary plan view of the heating members of the invention taken on line 11-11 of Fig. 10.

One type of flat precoated box blank which may be decoated in desired spots for facilitating gluing or other purposes is shown at 20 in Figs. 2-4. It will be obvious the other types of blank may also be decoated on the machine by merely substituting heating elements in the desired pattern of decoating. Blank 20 includes a bottom panel 21, opposite side wall panels 22 and 23, opposite end wall panels such as at 24, corner flaps such as 25 and 26 and diagonal tabs such as at 27 and 28. Suitable fold lines and slits define the various portions of blank 20 all in a well known manner and forming no part of this invention. A blank such as 20 is sometimes termed a four corner carton and it will be obvious that similar blanks, having an integral cover and wall panels and usually termed a six corner carton, may be decoated in a similar manner. Blank 20 includes an upper face 30 and an opposite lower face 31, each face being entirely covered with a coating such as wax 32 to make the carton water resistant. It is the presence of the wax coating 32 on the corner flaps such as 25 and 26 and on the diagonal tabs such as 27 and 28 that prevents the glue, applied thereto before folding, from securing a good firm adhesion.

The machine of this invention, as indicated in Fig. 3, is designed to apply heating surfaces such as 35, 36, 37 and 38 to the appropriate flaps and tabs such as 25, 26, 27 and 28 to volatilize the coating 32 and leave a surface area or spot uncoated and capable of glue adhesion thereon.

Thus as shown in Fig. 4 a surface area or spot 39, 40, 41 and 42 is decoated from each adhesive flap, tab or other portion of the carton to be glued, after folding, and without removing any substantial section of the coating which might cause the carton to lose its water resistant character. The corner flaps 25 and 26 are shown turned backwardly on their lines of articulation to reveal the decoated areas on the lower face 31 thereof, for illustration purposes only, this not being a function of the machine.

The machine of the invention includes a frame 44 formed of a pair of elongated side frame pieces 45 and 46 rigidly connected laterally by suitable cross frame pieces such as 47 and lateral shafts such as 48 to support the operating parts of the machine.

A pair of oppositely disposed members 50 and 51 are positioned midway of the length of the frame 44, member 50 being normally spaced above, and member 51 being normally spaced below the horizontal paper line P of the machine. Members 50 and 51 are substantially identical and each preferably comprises a pair of longitudinally extending plates such as 52 and 53, 252 and 253 each supported on a laterally extending channel member such as 54 or 55 by threaded clamping means such as 56 whereby the plates may be easily moved laterally to any asoasae desired position required by the dimensions of a blank such as 20. Each plate such as 52 is provided with longitudinally extending tracks such as 57 and 58 (see Fig. 11) for supporting heating elements such' as 59 and 60, set screws 61 being provided to permit longitudinal movement of the elements with relation to theplates. Each heating element such as 59 is substantially rectangular and preferably includes a removable plate 63 of brass, or other suitable metal, each plate 63 having an outer blank engaging surface such as 35, 36, 37 or 38 in the outline of the area desired to be decoated on the adjacent face of the blank as indicated in Fig. 3. Each heating element such as 59 also includes one or more electric resistance units of a well known type arranged to maintain the plate 63 and its blank engaging surface at a predetermined temperature and each plate is supplied with electric power from a source not shown through cords such as at 64.

At least one of each pair of opposed heating elements such as 59 and 66 (see Fig. 7 for example heating element 59;, is yieldably mounted by means of coil springs such as 67 in order that its heating plate 63 and blank engaging surface 37 may accommodate itself flatwise against the corresponding surface of the other element.

The channel members 54 and each terminate in a cross bar such as 71 and 72 (see Fig. 8), the cross bars having holes such as 73 and '74 centrally thereof to enable thechannel members 54 and 55 to slide vertically toward and away from each other on upstanding posts 75 and 76. Posts 75 and 76 form vertical axes fixed relative to the machine and are supported intermediate thereof by brackets 77 and 78 each fixed to a side frame piece 45 or 46. Each post such as 75 terminates at each opposite end in a cross arm 80 and 81 fixed thereto by a bolt 82 and 83.

The means for moving heating members 50 and 51 on their fixed vertical axes relative to the machine preferably includes coil springs such as 85 and 86 positioned between each cross arm such as 88 and 81 and the adjacent cross bar such as 71 and 72. The channel members 54 and 55 with their respective heating members are thus continually urged toward each other at the predetermined pres: sure exerted by the springs. The moving means for the members 50 and 51 also includes projecting cam followers such as the rollers 87 and 88, each rotatably mounted on the outside of a cross bar such as 71 or 72 of the channel members 54 and 55. As best shown in Figs. 8, 9 and 10 a pair of earns 89 and 90 are provided, each being of particircular shape and carried at the end of a radial arm such as 92 and 93, fixed to a lateral shaft 94 journalled at each opposite end 95 and 96 in a side frame piece 45 or 46. A crank arm 97 is fixed to shaft 94 and pivotally connected at 98 to a connecting rod 99 having a yoke cam follower 100 at its opposite end. Cam follower 100 encircles an eccentric cam 101 mounted on lateral shaft 102, the shaft 102 being journalled at each opposite end as at 104 and 105 in a side frame piece 45 or 46. Each cam 89 or 90 includes a wide portion 186 and a narrower portion 107, joined by an inclined plane portion 108, and each cam is located between a pair of cam follower rollers such as 87 and 88. As shown in Fig. 9 the wide portions 106 of the cams 89 and 90 hold the upper and lower heating members 50 and 51 in separated or open position against the constant pressure of springs 85 and 86. Rotation of shaft 102 causes the cams 89 and 90 to move in an arcuate path to bring first the inclined portions 108 and then the narrower portions 107 of the cams between the rollers 87 and 88 as shown in Fig. 10. Spring pressure thus forces the heating members together and causes the blank engaging surfaces thereof to engage with the opposite faces of a blank positioned in registration therebetween. The return movement of the cams 89 and 0 forces the rollers up the inclined surfaces at 108 onto the wider portion 106 of the cams, thus causing the heating members 50 and 51 to each rnove away from the adjacent face of a blank positioned in the space between the members.

Conveyor means, preferably in the form of a pair of parallel endless chains 110 and 111 is provided for moving the blanks individually and successively along the paper line P of the machine. The endless chains 110 and 111 extend from blank feeding means 112 at the blank feeding station 113 longitudinally of the machine, with the upper stretches 114 and 115 thereof passing horizontally through the space between the normally separated heating members 50 and 51, and continuing to a point beyond said members at the opposite end of the machine. Normally a stacking apron such as 116 is located at the delivery end of the machine to receive the blanks after they have been treated by decoating at the treating station 117 formed by the heating members 50 and 51. The blank feeding means 112, to be described hereinafter feeds each bottom blank such as 20 from the stack of blanks 118 and delivers it to the upper stretches 114 and 115 of the conveyor.

Each conveyor chain such as 110 is trained around one of a pair of spaced apart tension sprockets such as 120 fixed to a stub shaft 121 and thence upwardly around one of a pair of sprockets such as 122 fixed to a lateral shaft 123. The upper stretches 114 and 115, as stated above, then extend along paper line P the full length of the machine at which end each is trained around one of a pair of spaced sprockets such as 124 fixed to lateral shaft 48. Each chain then extends in its lower stretch 125 to its tension sprocket such as 120.

Shaft 48 carries a sprocket 127 connected by a chain 128 to a sprocket 129 carried by the shaft 102, there being a suitable tension sprocket 130 for maintaining proper tension. Thus as shaft 102 rotates to cause members 58 and 51 to move toward and away from each other, it also moves the endless conveyor chains 110 and 111 unidirectionally to cause the upper stretches 114 and 115 to continuously advance at a predetermined speed synchronized with the movement of members 50 and 51.

The register means 133 of the invention includes a plurality of spaced apart movable register lugs such as 134 each preferably pivotally mounted as at 135 to a link such as 136 of a chain such as 110 and 111. The pivotally mounted register lugs 134 on each chain are laterally aligned and each pair of laterally aligned pivoted lugs is spaced lengthwise from the next succeeding pair a distance at least as long as twice the longitudinal dimension of the particular type blank being treated on the machine. Midway of each space between each pair of laterally aligned pivoted lugs such as 134 on the chains 110 and 111 a pair of laterally aligned non pivoted register lugs such as 137 are mounted, each lug 137 being fixed to a link 138 of a chain such as 110 or 111. Register means 133 also includes a pair of parallel longitudinal path cams 139 and 140, each extending from proximate feeding means 112 to proximate the treating station 117 formed by heating members 50 and 51. The pivotally mounted register lugs 134 each include a slot such as 141 for a pin 142 projecting from a link 143 of a chain such as 110. The blank engaging head 144 of each lug 134 may thus be raised above the plane of the upper stretch 114 into the plane of paper line P and the path of the blanks by the path cams 139 and 140, or may be guided by the path cams to a position below said planes and path into a non blank engaging position. Each lug 134 also includes a cam follower pin such as 145 on its head portion 14-4 arranged to enter the path of the adjacent longitudinal cam such as 139 or proximate the feeding station 113, to remain so engaged and with the head 144 in blank engaging position up to a point proximate the treating station 117 and to then be moved downwardly by the path of the cam to cause the head 144 to be forced downwardly below the plane of the paper line into non blank engaging position.

At the commencement of the upper stretches 114 and 1 15 of chains 110 and 111, near the feeding station 113, both the pivoted lugs 134 and the alternately spaced,

fixed lugs 137 have their blank engagingheads such as 144 extending above the paper line ready to engage the trailing edge of a blank fed onto the endless conveyor. However, blanks are fed individually and successively only to each pair of laterally aligned lugs 134 with no blanks being fed to the fixed lugs 137. When the pivoted lugs 134 arrive at the end of longitudinal cams 139 and 140, the heads 144 thereof are moved below the paper line P to instantly release the blank from the continuously advancing chains 110 and 111. The blank such as is thus deposited in a position of registration between the spaced apart heating members and 51 just as the heating members are brought together to temporarily apply heat to the portions of the blank to be decoated or dewaxed. Application of heat by the heating elements such as 59, 60, and 66 is continuous until just before the arrival of the next succeeding pair of fixed lugs such as 137 at the treating station 117. Thereupon the heating members 50 and 51 each move away from the treated blank to enable the blank to be reengaged by the chains through lugs 137 and advanced to the end of the machine in registration.

Preferably blank retarding means is provided, means 150 comprising a plurality of longitudinally spaced resilient spring members such as 151. A pair of longitudinal supports 152 and 153 are mounted parallel to each other to extend lengthwise above paper line P. Supports 152 and 153 are carried by brackets such as 155 and 156, the brackets depending from lateral frame rods such as 157 and 158. Spaced along the supports 152 and 153 are the resilient spring members 151, each having its base portion 159 mounted thereon for angular adjustment to various positions by set screws 160 and 161. The leaf springs 151 each extend downwardly in the direction of travel of the blanks through the machine and terminate in an elongated foot portion 162 extending below but nearly parallel to the plane of the paper line. The springs 151 are angularly positioned to cause the foot portion 162 thereof to bend to a horizontal position and exert.

faces of the blanks passing therebelow without forming a stop therefor and without damaging the coating on the blanks.

Blank retarding means 150 also includes a straight longitudinally extending rail such as 163 at the level of the path of the bottom face of each blank 20 along the paper line P, each rail 163 being positioned beneath each line of spring members 151 to support the blanks against the downward pressure thereof. It is preferred that each rail 163 be a cover or guard for a conveyor chain such as 110 or 111 whereby the blanks ride on the rails and at no time contact the chains. The register lugs are alongside the chains and project upwardly alongside the rails 163 to advance the blanks. By means of the retarding force of the spring members 151 and rails 163 the blanks are firmly held against the lugs 134 and 137 and maintained in registration with the conveyor chains. Preferably at least one laterally aligned group of retarding springs such as 151 each extends longitudinally into the treating station 117 intermediate of the heating members 58 and 51 as shown in Figs. 6 and 7 to assist in causing the blank to be released in the proper position for decoating.

One or more clamping elements such as 165 are preferably provided for securing an additional yieldable and frictional grip on the opposite faces 30 and 31 of each blank 20 to further insure the positioning of the same in registration at the treating station 117. Each clamping element 165 is movable and depends from the channel member 54 over each rail 163 by means of a bracket 167. Bracket 167, as best shown in Figs. 6 and 7, includes integral lug 168 and movable lug 169 for embracing a side wall of channel member 54, lug 169 being tightenable by a threaded knob 17 9 whereby the bracket may be laterally positioned at any point desired. A vertical rod 171 is slideable in an opening 172 in bracket 167 with a stop nut 173 at its upper end and a cylindrical rubber pressure element 174 at its lower end. A coil spring 175 continually urges element 174 downwardly but permits upward yielding by compression of the spring. The blank engaging frictional surface or clamping surface 176 of element 174 is normally poised just slightly above the plane of the path of the upper face 30 of each blank 20 passing along paper line P and is normally below the plane of the retracted heating surfaces such as 37 on the upper heating member 50. Thus upon the closing movement of the upper member 50 toward the paper line and toward the lower member 51, surface 176 immediately engages the upper surface 30 of a blank 20 and remains so engaged while spring 175 compresses and until the heating elements such as 59 also engage the blank.

The rails such as 163 each constitute a stationary clamping jaw for the movable clamping jaws such as 165. Each rail such as 163 is supported by suitable posts such as 180, mounted on a lateral frame member 181, and includes a fiat blank supporting upper surface such as 182 co-planar with the blank supporting surface of the stretches 114 and 115 and the path of the lower face 31 of a blank 20. While springs 151 continually retard the blanks 20 by exerting frictional yieldable downward pressure on face 30 thereby pushing face 31 frictionally against the rails such as 163. The downward pressure of movable clamping element 165, opposed by the immovable rails such as 163 is a positive clamping action exerted on opposite faces of the blank to halt all advance thereof;

The blank feeding mechanism of this invention is useful for feeding sheets or blanks which are uncoated as well as coated and is therefore the subject of a separate co-pending application by me, Serial No. 494,731, filed March 16, 1955. The blank feeding mechanism 112 at the blank feeding station 113 includes a bottom feed magazine 184 adapted to support a stack 118 of blanks such as 20. The fact that the blanks being treated in the machine of this invention are coated on both faces with material such as wax causes ordinary feeding machinery to be somewhat inefiicient. For example, a rotating feed wheel having a rubber insert or the like for periodically frictionally engaging the face of a blank to advance it through a blank passage might tend to slip on the coated blank face and might also accumulate a coating of wax on the insert.

As shown in Figs. 1 and 5 the feeding mechanism 112 of this invention is designed to secure an initial positive grip on a large area of the bottom face of the bottom blank of the stack, to then advance the gripped blank through blank separator means into the nip of a pair of rolls and to then release the grip on the blank to permit the rolls to advance the blank into the path of the pivoted register lugs 134.

The magazine 184 includes side stack guides such as 185, a forward wall formed by a separator or gate member 186 and a bottom formed by a plurality of laterally spaced longitudinal bars such as 187 and 188 supported on lateral frame pieces 190 and 191. The lower edge 192 of separator member 186 is spaced the thickness of one coated blank 20 from a fixed separator member 193 to form a blank passage 189, opposite the leading edge of each successive bottom blank in the stack, which will accommodate only one blank at a time. Separator member 186 is supported on links 194 and 195 and includes a block 196 spring pressed downwardly by a spring 197 on a fixed adjusting rod 198 whereby it may yield up wardly. The leading edge of a single blank 20, after passing between separators 186 and 193 enters the nip of the pair of rolls 199 and 200, the circumference and rate of rotation of the rolls being arranged to advance the blank entirely through the passage and out onto the endless chains 110 and 111. The endless chains 110 and 111 are trained around the sprockets such as 122 on the same shaft 123 that supports the lower roll 200 and the movable lugs 13.4 areraised above the'pa per line Pby means oflthe path cams 139 and 140 proximate the nip 202 of the rolls 199 and 200.

A carriage 203 is longitudinally slideable in fixed tracks 204 and 205 below magazine 134 and supports a plurality of suction cups such as 206and 207. The suction face or opening 208 and friction rim 209 of each cup such as 2% is fiatwise against the coated underface 31 of each bottom blank 20 and advances in a flat plane toward and away from the passage 189. Flexible and rigid tubes such as 210 connect each cup 206 or 207 to a suction control valve 211 by which the suction cycle of the cups is synchronized with the other moving parts of the machine. Suction valve 211is connected to a source of air suction of any well known type not shown in the drawings, and preferably also to a source of air pressure not shown.

The suction control valve 211, as described in detail in the above mentioned covpending application is arranged to exhaust air from cups 206 and 207 during the forward movement of carriage 203 and preferably to blow air through the cups 206 and 207 on the rearward movement of the carriage to urge the bottom blank of the stack and the stack itself away from the cups and thus avoid friction. A bell crank lever 212 is pivotally mounted on a lateral shaft 213 supported on frame 44 and one arm 214 thereof is slotted at 215 to receive a laterally projecting lug 216 on carriage 203. A pair of levers such as 212 may be provided one on each side of carriage 203 if desired. The other arm 218 of lever 212 includes a roller follower 219 engaged in a cam track 220 of a rotatable cam 221 mounted to revolve with a lateral shaft 222.

A main drive chain 225 is trained around a sprocket 226 on shaft 102 thence around a sprocket 227 on shaft 222, thence around a sprocket 223 on shaft 123, thence under a tension sprocket 229 on a stub shaft 230 and thence back to sprocket 226.

As shown in Fig. 5 a gear reducer 231 of a well known type rests on a platform 232 and drives the shaft 102, the source of power being a shaft 233 and a pulley 234 as shown or a separate electric motor.

A earn 237 on shaft 222 includes a cam surface which engages a movable element on control valve 211 for synchronizing the action of the valve with the feeding, conveying, registering and treating means of the machine. It should be noted that each heating element such as 59 of the invention is opposed by another heating element on the opposite face of the blank rather than by an unheated clamp as in prior devices. While the exposure to heat of both faces of the blank, when only 'one face is desired to be decoated, may volatilize some of the coating in undesired areas such exposure does not cause the carton to leak and does assure a satisfactory glued joint. It has been discovered that applying heat to only one face of a blank, affects the coating on the other face in any case and also tends to cool the heating elements to the point that they are ineffective when operated at the speeds required. Thus the advantages of simultaneously heating opposite areas on the opposite faces of the blank overcome the disadvantages of heating only the area of the face desired to be dec-oated.

I claim:

1. A machine for spot removal of coating from precoated flat box blanks, said machine comprising a pair of oppositely disposed, spaced, members, each having electrically heated elements directly opposed in register with each other and arranged to engage predetermined areas on the opposite faces of a blank positioned in registration therebetween; means for moving at least one of said members toward and away from the other on a fixed axis relative to said machine; an endless chain conveyor having a stretch arranged to convey individual and successive blanks from a stack of blanks through the space between said members to a point beyond said members;

means for continuously advancing thestretch of said con veyor unidirectionally at a predetermined speed .synchronized with the movement of at least one said member; and register means, including alternating, spaced, fixed and movable register lugs on said chain conveyor and cam means for moving the movable lugs into and out of blank engaging position, for engaging and moving each successive blank to a position of registration between said members, temporarily releasing said blank from movement with said chain at said position and then re-engaging and moving said blank away from said position in registration with said chain.

2. A machine as specified in claim 1 wherein both of said members are normally spaced out of the path of a blank carried on said chain and both of said members are mounted to move toward a blank positioned therebetwcen.

3. A machine as specified in claim 1 wherein the means for moving said members comprises springs for urging said members toward each other and cams for forcing said members away from each other against the pressure of said springs.

4. A machine as specified in claim 1 wherein said endless chain conveyor includes a pair of parallel, longitudinally extendingroller chains spaced apart to support said blanks on each opposite side of the longitudinally extending centre line thereof and said movable register lugs are each pivoted to the pin of one roller and guided on the pin of a succeeding roller of said roller chains.

5. A machine as specified in claim 1 wherein said cam means comprises a longitudinally extending path cam on said machine adapted to cause said movable register lugs to move into and out of blank engaging position relative to said chain.

6. A machine as specified in claim 1 wherein said movable register lugs are each pivoted to said conveyor.

7. A combination as specified in claim 1 plus blank retarding means on said machine, operable on the opposite faces of each blank for yieldably and frictionally urging each successive blank into firm engagement with said register lugs.

8. A combination as specified in claim 7 wherein said blank retarding means includes a plurality of resilient leaf springs spaced apart longitudinally of said machine, each having a free foot portion extending substantially parallel to and in the direction of movement of a blank for flatwise engagement with the adjacent face of a blank.

9. A combination as specified in claim 1 plus blank clamping means including a yieldable clamping element mounted to move with one of said pair of oppositely disposed spaced members, said element having a clamping face adapted to engage the adjacent blank face before the engagement of the heating elements on said member with said blank face and including an immovable unyielding clamping element opposed to said yieldable clamping element for engaging the other face of a blank.

10. A combination as specified in claim 1 plus blank retarding means including a plurality of spaced longitudinally aligned resilient leaf springs above the paper line on said machine for exerting downward pressure on the upper face of each blank passing therebelow, a longitudinally extending rail below the paper line on said machine for supporting the lower face of each said blank pressed down by said springs and at least one yieldable I clamping element, movable with said heating elements on a fixed axis relative to said machine for clamping each successive blank down on said longitudinally extending rail.

11. In a machine for treating fiat box blanks, said machine having a blank feeding station, a blank treating station and a uni-directional, endless, continuously moving blank conveyor passing through said stations, the combination of a plurality of fixed registration lugs spaced around said conveyor and adapted to engage a blank supported on said conveyor to advance the same therewith; a

plurality of movable registration lugs, each located centrally of the space between each adjacent pair of fixed registration lugs and each having a blank engaging and a blank disengaging position; means at said blank feeding station for moving said movable registration lugs into blank engaging position, means at said blank treating station for moving said movable registration lugs into blank disengaging position and means at said feeding station for feeding individual blanks successively in front of said movable registration lugs but not in front of said fixed registration lugs.

12. A combination as specified in claim 11 wherein said movable registration lugs are pivoted to said conveyor and the means for moving the same comprises a rigid path cam in the path of a portion of said lugs and extending longitudinally from said feeding station to said treating station.

References Cited in the file of this patent UNITED STATES PATENTS 

